One proposed vehicle skid control device restricts the torque level output from a motor to drive wheels on the occasion of the occurrence of a skid of the drive wheels caused by the torque output from the motor (see, for example, Japanese Patent Laid-Open Gazette No. 10-304514). This proposed device detects the occurrence of a skid according to an increase in angular acceleration of the drive wheels over a preset threshold value and lowers the torque level output from the motor in response to detection of the occurrence of a skid, so as to reduce the skid. The angular acceleration of the drive wheels may, however, exceed the preset threshold value, due to another cause, for example, some vibration of the vehicle at a start of an engine or due to a significant torque change. This may result in misdetection of a ‘phantom’ skid, which actually does not exist.
There is another proposed technique that sets a significantly large value to the threshold value representing the occurrence of a skid of the drive wheels under the condition of an abrupt increase in accelerator opening or a significant time variation of the accelerator opening and thereby eliminates effectiveness of the skid control (see, for example, Japanese Patent Laid-Open Gazette No. 3-156135). This proposed technique, however, aims to keep the sufficient response of the vehicle body in the event of an abrupt increase in accelerator opening and does not give any consideration to unnecessary restriction of the driving torque in response to misdetection of a ‘phantom’ skid.
In order to eliminate the drawbacks of the prior art discussed above, the object of the invention is to provide a vehicle skid control device and a corresponding vehicle skid control method that prevent unnecessary restriction of driving torque in response to misdetection of a ‘phantom’ skid, which actually does not exist, in angular acceleration-based skid state determination.